Electromagnetic relay



March 24', 1942. c. T. EVANS 2,277,553

ELECTROMAGNETIC RELAY Original Filed July 20, 1939 Patented Mar. 24, 1942 ELECTROMAGNETIC RELAY Clarence .1. Evans, Wauwatosa, Wis, aleignor to Cutler-Hammer, Inc., Milwaukee, Win, a corporation of Delaware Original application July 20, 1939, Serial No.

comma. This invention relates to electromagnetic re lays, and, while not limited thereto, the invention relates more particularly to apolarized relay which upon response controls the circuit of a translating device.

This application is a division of my copending application, Ser. No. 285,533, illed July 20, 1939, for a Voltage regulator.

An object of the invention is to provide a relay which is very sensitive to variations of the control current.

Another object is to provlde a relay which is Divided and this application May 23, 1940, Serial No. 336,707-

tion or the other when the pulls upon the two cores l5 differ from each other. The bracket I3 is provided with a depending extension I! which carries a horizontal pin I1 and a biasing spring i8 is interposed between the same and the foot portion 5 of bracket 4 so as to bias the armature I! normally to thecentral or intermediate position thereof illustrated.

Riveted to the central part of the lever l4, but ofiset upwardly from the latter, as by means of an interposed metallic spacer, is a double-ended contact spring l9 which carries at each end a contact button 20, which buttons are selective- 1y movable into engagement with adjustable stationary contacts 2| respectively associated there with which are screw-mounted on brackets 22,

bodiment of the invention as applied to a centerbiased polarized relay.

In the drawing, Figure 1 is'a vertical cross section of a relay embodying the invention.

Fig. 2 is a vertical transverse cross section of the relay, on the line 2-2 .of Fig. 1.

Fig. 3 is a diagram of connections of a control system embodying the relay illustrated in Figs. 1 and 2.

Referring to Figs. 1 and 2 the relaycomprises a bracket l which is arranged to be supported from an insulating base 2 by means 0! screws or other holding means 3. Attached to the bracket 1 is a second bracket 4. The bracketl is made of strip metal and comprises a horizontal foot portion 5 by means of which it is fastened to the bracket i, a vertical portion 6 bent upwardly at a right angle to the foot 5, a horizontal top portion 1 which is parallel to the foot 5 and a depending vertical portion 8 which is in a plane at right angles to the plane of foot 5 and parallel to the portion 6. The portions 6 and 8 are provided with aligned bearings 9 and Ill to receive a horizontal shaft ii for pivotal support of an armature l2. The armature l2 comprises a horizontal lever I4 to which is attached a bearing bracket [3. At each end the lever l4 carries a magnetizable core l5, said cores being preferably of U-shape as illustrated. Each of the magnet cores i5 is surrounded by three magnetizing coils as will be explained heerinafter. The lever 14 is pivotally supported by bracket l3 upon the pivot shalt II and is rotated thereabout in one directhe brackets 22 being supported by the insulat-.

ing base 2 and each being provided with a ter-' minal 23 for the attachment of a circuit wire leading thereto for connection of the respective stationary contacts in the respective circuits.

As shown in Fig. 2 bracket l3 has attached to its extension It, as by spot-welding, one end of a wire or pigtail 39, the other end of which is attached by a screw 4!! to the portion 6 of bracket 4. By the means illustrated a good electrical connection is provided between the contact spring i9 and bracket 4; the securing screws 4| insuring a good mechanical and electrical connection between brackets I and 4, and a soldertype wiring terminal 42 (Fig. 2) being clamped in position by one of the screws 4! to provide I for connectionof a third wire common to the two circuits shown diagrammatically in Fig. 3.

It will thus be apparent that if the armature is rotated in one direction or the other a circuit is closed between a contact button at on spring 19 and one or the other of the stationary contacts 2i.

Referring now to Fig. 3 the same illustrates a power supply system represented by lines L and L and a sender potentiometer 30 having a resistance 30 which is connected between thelines L and L and which is provided with an adjustable contact brush 30 A'relay 3| like that just described is provided with three pairs nf'magne tizing coils 32, 32 33, 33 and 34 34 respectively, one coil of each pair surrounding one of the armature 12 in opposite directions thereby tending to balance the latter.

The system further includes a group of lamps and a lamp illumination intensity regulator in the form or a rheostat or transformer 33 the winding of which is connected across the lines L L The lamp regulator 33 i provided with a movable contact brush 33' which connects ditterent taps of the-regulator 33 to the bus bar 36'. The brush 33' may be moved to different taps by a screw 38 which is operable selectively by a pair of motors 31' and 31" rotatable in opposite directions respectively. A receiver potentiometer rheostat 33 has a resistance 38 which is connected across the lines L and U and which is provided witha sliding contact brush 38', which connects the rheostat to the bar 38. The brush 38" is attached to and movable simultaneously with the brush 36' so that the position of the former always corresponds to the illumination intensity oi the lamps 35. The pair of coils 32" and 32" on the left and right hand cores respectively 01' the relay are so connected relatively to each other and to the pair of coils 84 and 34" that a current flowing in one direction or the other in the former pair of coils modifles or counteracts the balanced pull oi the latter pair of coils upon the cores l5 whereby the armature I! (see Fig. l) and consequently the contact spring I! are rotated or tilted in one direction or the other. lhe

coils 32' and 32 are connected in series between the brush 30 and the contact bar 38. Hence -if there is a potential diflerence between the,

brushes 30 and 88 this is impressed upon the coils 32' and 32 and the resulting current unbalances the relay so that its armature is rotated in one or the other direction, depending upon whether the lamp intensity and therefore the voltage of potentiometer brush 38 i higher orlower than the desired intensity, which corresponds to the position of the brush 30 The movable contact buttons of the relay are both connected to line I), while-one terminal oi each of the operating windings 31 and 31 respectively. oi the motors 31- and 31 is connected to line L and the other terminals of the respective windings are connected to the terminals of the left hand and right hand stationary contact 2!,

respectively, of the relay. Hence if the lamp voltage differs from the desired value corresponding to the position of brush 3t the armature i2 is rotated or tilted, and consequently one or the other of the motors 31'- or 31 is energized to change the position of the brush 38* and thus provide the desired lamp brilliancy.

As the system again approaches the balanced condition the current in the coil 32' and 32 approaches zero and the torque exerted by the the operating windings 31 and 31 of the motors 31' and 31", respectively. Thus as soon and as long as either motor is energized an additional torque is exerted upon one or the other core ll of the relay to increase the pressure of the active contact button 20 against its associated stationary vcontact 2| to thereby prevent chattering or 'vibration of the armature and arcing at such contacts. It will be observed that the coils 33- and 33" are permanently connected across the supply lines in series with the respective coils 31' and 31 But the current flowing therethrough when both motors are disconnected afiects the pull on the respective relay cores II equally but in oppomte directions and therefore they do not unbalance the relay. Furthermore the pull is very low because the inductance of the circuit is relatively high. If, however, current flows through one of the motor operating windings. a. supplemental voltage is induced in the respective coil 31 or 31. which unbalance; the pull exerted by the coils 3! and 33 and substantially increases one or them which assists in maintaining the relay contacts closed until the current in coils 32 and 32 i again substantially zero, at which time the only unbalanced torque remaining is due to the coils 33 and I3".

which s insuflicient to maintain the relay contacts closed, whereupon they open and disconnect the respective motor and this again establishes equal current flow in the coils 33 and 33".

Furthermore, if it should be desirable to increase the natural sensitivity of the relay, the coils 31 and 3'! may be connected in the re verse way from that described so that upon energization of the respective motor winding 31 or 31, the unbalanced pull on the relay armature II by coils 32* and 32 is decreased or counteracted by the tendency of coil3l or 31 (as the case may be) to open or disengage the active pair oi relay contacts 20, 21, thus decreasing the range between the closing pull required to be exerted by the coils 32" and 32 and the point at which the pull of said coils for effecting closure of one or the other of the sets of contacts 20, 2| is neutralized to permit opening thereof by the balancing elements.

What I claim as new and desire to secure by Letters Patent is:

1. A polarized relay for controlling a pair of circuits comprising, a center pivoted lever, means to bias said lever to a neutral position, contacts for selectively energizing one of a pair of circuits in response to departure of said lever from said neutral position in opposite directions, a magnetizable core attached to each end of said lever, auxiliary windings adapted when energized to produce equal fluxes in said core resulting in balanced torques on said lever, control windings adapted when energized to cause a current flowing therein to increase one and to simultaneously decrease the other of said fluxes by substantially equal amounts, and compound windings respec tively connected in a circuit energized by thecurrent flowing in the respective circuit and adapted to cause said current to induce a supplemental flux in the respective core which is a function of the current of said respective circuit.

2. A polarized relay for controlling reversible motor means comprising, a center pivoted lever, means to bias said leverto a neutral position, contacts for reversibly energizing said first mentioned means in response to the departure of said lever from said neutral position, a magnetizable core attached to each end of said lever, auxiliary,

-ings respectively and compound windings, connected in acircuit energized by the current flowing in said motor means and adapted to cause said current to induce a supplemental flux in said cores which is a function of the current of the motor means. I i

3. A polarized relay for controlling reversible 7 motor means comprising, a center pivoted lever,

means to bias said lever to a neutral position,

. contacts for reversibly energizing said first mentioned means in response to the departure of said lever .irom said neutral-position, a magnetizable core attached to each end of said lever, an auxiliary coil surrounding each core and adapted when energized to exert equal pulls on said cores tending individually to rotate said lever in opposite directions, a control coil on each core, said control coils when energized increasing and decreasing the pull on their respective cores by equal amounts, said increase and decrease depending upon the magnitude and direction of the current flowing in said control coils, and a compound coil on each core connected in a circuit energized by the current f'flowing in said motor means and adapted when energized'to ex ert a supplemental pull on the respective core which is a function of the current of the motor means. 7

4. A; polarized relay for controlling reversible motor means comprising, a center pivoted lever,

'meansto bias said lever to a neutral position,

contacts for reversibly energizing said first mentioned means in response to the departure of said lever from said neutral position, a magnetizable core attached to each end of said lever, an auxiliary coil surrounding each core and adapted to induce fluxes therein resulting in individual pulls thereon tending to rotate said lever in opposite directions, a control coil on each core, said control coils when energized increasing and decreasto induce a supplemental flux in the respective core, which is a' function of th current of the motor means.

CLARENCE T. EVANS. 

